Geolocation and positioning technology, such as the satellite-based Global Positioning System (GPS), offer commercially attractive opportunities to provide any number of useful location-based services to users of cellular handsets and other mobile devices, such as turn-by-turn directions, mapping of nearby points of interest and landmarks, and targeted emergency assistance.
Accessing such technology can be taxing for a multipurpose mobile device that has less power to spare than a dedicated device such as a GPS receiver. In addition to traditional voice features, ancillary features such as email and other messaging applications, internet browsers, games, music, and geolocation applications consume processing resources in the mobile device and strain battery power. Furthermore, certain geolocation and positioning technologies also sap the resources of the communications network that serves the mobile devices.
For example, GPS signals shift in frequency due to the relative motion between a handset-based GPS receiver and the constantly moving GPS satellites. This Doppler frequency shift requires the GPS receiver to find the frequency of the signal before the GPS receiver can lock onto the signal and make a determination of location. To do so, the receiver may need to search the entire frequency range.
Many GPS equipped mobile devices also supplement GPS with adjuvant technologies such as Time of Arrival (TOA), Enhanced Cell Identification, and Assisted Global Positioning System (A-GPS). For example, A-GPS uses a combination of GPS satellites and cellular network base stations to more accurately and/or more rapidly pinpoint the location of a GPS receiver associated with a mobile device. The mobile device GPS receiver correlates an estimation of the mobile handset location as determined by a cell-sector to more accurately predict the GPS signal the handset will receive. With this assistance, the extent of the frequency search space is reduced and the time-to-first-fix (TIFF) of the signal is reduced from minutes to seconds. A-GPS handset receivers can also detect and demodulate signals that are weaker in magnitude than those required by a traditional GPS receiver.
Although these hybrid architectures can increase battery conservation capabilities of the mobile device, constantly querying the cellular network and/or GPS satellite network represents an ongoing drain of battery power in addition to a strain on communications networks.
Regardless of the technologies that are used, continuous location tracking is typically provided as long as the device is powered on and any location-based application is activated. Location data is continually fed to and output from each location-based application at the highest-resolution that the device and network can access. However, location data at such fine resolution is not continually used by or useful to the user. For example, most users of turn-by-turn navigation services are familiar with at least part of the selected route—often, the origination point of the trip is a user's home city. A user will program a navigation system at the start of the trip nonetheless, so that useful directions will be available when needed.
Continuous tracking of device location at fine resolutions consumes substantial battery power, sometimes to the extent that user behaviors are adapted to compensate. For example, to extend battery life, a user may manually deactivate location functionality of the mobile device when location information is not needed. It is easy to imagine that the user may then forget to reactivate the functionality when location is needed and have to wait for the system to boot up and acquire the data.
Therefore, there is a need in the art for an intelligent system that automatically optimizes utilization of mobile network and handset resources dedicated to providing geolocation and location-based services to mobile devices.